Error while using List.asmx

I get this error whenever I work with List.asmx 

The content type text/html; charset=utf-8 of the response message does not match the content type of the binding (text/xml; charset=utf-8). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly. The first 70 bytes of the response were: 'The handle is invalid. (Exception from HRESULT: 0x80070006 (E_HANDLE))'.

Why does this error come?